Chronic non-specific neck pain is a common musculoskeletal disorder that significantly affects quality of life and functional ability. Conventional treatments often provide limited relief and may be associated with adverse effects. Acupuncture and Chinese herbal fumigation are commonly used therapies in traditional Chinese medicine and have shown potential benefits in pain relief and functional recovery.

This multicenter randomized controlled trial aims to evaluate the efficacy and safety of acupuncture combined with Chinese herbal fumigation in patients with chronic non-specific neck pain. A total of 120 participants will be randomly assigned to three groups: acupuncture combined with Chinese herbal fumigation, acupuncture combined with sham fumigation, and acupuncture alone. All participants will receive five treatment sessions within three weeks, followed by a four-week follow-up period.

The primary outcome measure is pain intensity assessed using the Visual Analog Scale (VAS). Secondary outcome measures include the Neck Disability Index (NDI), cervical range of motion, Pittsburgh Sleep Quality Index (PSQI), quality of life scale, and Central Sensitization Inventory (CSI). This study aims to provide high-quality clinical evidence regarding the effectiveness of acupuncture combined with Chinese herbal fumigation for chronic non-specific neck pain.

Background and Rationale Chronic non-specific neck pain is a prevalent musculoskeletal condition and a leading contributor to disability worldwide. It is characterized by persistent pain, stiffness, and functional limitation without a clear underlying structural pathology. Although conventional treatments such as non-steroidal anti-inflammatory drugs, physical therapy, and exercise are widely used, their effectiveness is often limited and may be associated with adverse effects. Traditional Chinese medicine offers alternative therapeutic strategies, including acupuncture and herbal fumigation. Acupuncture is believed to unblock meridians and regulate pain pathways, while Chinese herbal fumigation combines thermal stimulation with transdermal absorption of medicinal components to improve local circulation and reduce inflammation. Despite their complementary mechanisms, high-quality randomized controlled trials evaluating the combined effect of these two therapies for chronic non-specific neck pain remain scarce. This study aims to address this gap by rigorously assessing the efficacy and safety of acupuncture combined with a standardized herbal fumigation formula.

Study Design and Setting This study is a multicenter, randomized, parallel three-arm controlled clinical trial. It will be conducted at two traditional Chinese medicine outpatient centers in Malaysia. The study will enroll 120 eligible participants who will be randomly allocated in a 1:1:1 ratio to one of three groups: (1) acupuncture combined with Chinese herbal fumigation, (2) acupuncture combined with sham fumigation, and (3) acupuncture alone. An assessor-blind design will be employed to minimize bias, meaning that outcome assessors and data analysts will be unaware of group allocation.

Participants and Eligibility Participants will be recruited from outpatient clinics, bulletin boards, and online health platforms. Eligible individuals must be aged 18 to 65 years, have chronic non-specific neck pain lasting at least three months, present with a Visual Analog Scale score of 4 or higher, and demonstrate a reduction in cervical range of motion of 20% or more. Both Western diagnostic criteria and traditional Chinese medicine pattern differentiation for "cold coagulation type" neck pain must be met. Key exclusion criteria include confirmed organic pathology (e.g., disc herniation, infection, tumor), severe systemic diseases, pregnancy, lactation, receipt of other neck pain treatments within the past month, open wounds or skin lesions in the treatment area, and known allergies to acupuncture needles or herbal components.

Interventions The treatment period consists of five sessions delivered over three weeks, approximately twice per week. A follow-up assessment will be conducted four weeks after the final treatment.

Acupuncture Combined with Chinese Herbal Fumigation Group: Participants receive acupuncture at bilateral cervical Jiaji points (EX-B2) using single-use sterile needles (0.30 × 40 mm). Needles are retained for 20 minutes with manipulation to achieve deqi. Fumigation is performed using the Wenyang Tongluo Fumigation Formula, a proprietary herbal blend prepared as a powder (30 g) and decocted with 1000 mL of water. Participants lie supine while the neck area is exposed to steam from a fumigation bed. The steam outlet is positioned 30 cm from the neck, with temperature controlled: 35°C for 3 minutes, followed by 40°C for 30 minutes.

Acupuncture Combined with Sham Fumigation Group: The acupuncture protocol is identical to the combined therapy group. Fumigation is performed using 1000 mL of pure water without any herbal components, under the same temperature and duration conditions. This design isolates the thermal and environmental effects of fumigation.

Acupuncture Alone Group: Participants receive acupuncture at bilateral cervical Jiaji points using the same protocol as the other groups. No fumigation is administered.

Outcome Measures Outcomes are assessed at four time points: baseline (T0), immediately after the first treatment (T1), immediately after the fifth treatment (T2), and at the four-week follow-up (T3).

Primary Outcome: Pain intensity is measured using the Visual Analog Scale, a 10 cm horizontal line where participants mark their pain level, with scores ranging from 0 (no pain) to 10 (worst possible pain).

Secondary Outcomes:

Neck Disability Index: A 10-item questionnaire assessing the impact of neck pain on daily living and function. Scores range from 0 to 50, with higher scores indicating greater disability.

Cervical Range of Motion: Measured using a digital goniometer to assess flexion, extension, lateral flexion, and rotation. Values are recorded in degrees.

SF-36 Quality of Life Scale: Assesses health status across eight domains, including physical functioning, bodily pain, and mental health. Scores are standardized from 0 to 100, with higher scores indicating better quality of life.

Pittsburgh Sleep Quality Index: Evaluates sleep quality over the past month. Total scores range from 0 to 21, with higher scores reflecting poorer sleep.

Central Sensitization Inventory: A 25-item questionnaire measuring symptoms associated with central sensitization. Scores range from 0 to 100, with higher scores indicating greater sensitization.

Safety Assessment: Adverse events will be continuously monitored throughout the treatment and follow-up periods. All events will be recorded, classified by severity, and managed according to the study protocol.

Randomization and Blinding A computer-generated random number sequence will be created by an independent statistician. Allocation will be concealed using sealed, opaque, sequentially numbered envelopes. Due to the nature of the fumigation intervention, participants and acupuncturists cannot be fully blinded. However, outcome assessors and data analysts will remain blinded to group allocation throughout the study to minimize detection bias.

Statistical Analysis Data analysis will follow the intention-to-treat principle, with missing data handled using the last observation carried forward method. The primary outcome (VAS) will be analyzed using a mixed-design analysis of variance with group (three levels) and time (four time points) as factors. Post-hoc comparisons will be adjusted using Bonferroni correction. Secondary outcomes will be analyzed using similar repeated measures models or nonparametric tests as appropriate. Categorical variables will be analyzed using chi-square tests. A two-tailed significance level of P < 0.01 will be considered statistically significant. Effect sizes will be reported as partial eta-squared. All analyses will be performed using SPSS version 26.0.

Ethical Considerations and Data Management This study will be conducted in accordance with the Declaration of Helsinki. Ethical approval has been submitted to the Universiti Tunku Abdul Rahman Research Ethics Committee. Written informed consent will be obtained from all participants prior to enrollment. Participants may withdraw at any time without consequence. All data will be collected using electronic case report forms and stored in password-protected, encrypted servers accessible only to authorized personnel. Personal identifiers will be removed to ensure confidentiality.

Study Status Participant recruitment is expected to begin in May 2026 and be completed by February 2027. Data collection and follow-up are expected to be finalized by May 2027.

Inclusion Criteria:

• Aged 18 to 65 years, any gender
• Diagnosed with chronic non-specific neck pain lasting ≥ 3 months
• Visual Analog Scale (VAS) pain score ≥ 4
• Cervical range of motion reduced by ≥ 20% compared to normal range
• Conformity to both Western diagnostic criteria and Traditional Chinese Medicine pattern differentiation for "cold coagulation type" neck pain
• Voluntarily participate and provide signed informed consent

Exclusion Criteria:

• Presence of confirmed cervical disc herniation, nerve compression, or other specific pathologies (e.g., infection, tumor, fracture, etc.)
• History of cervical spine surgery or recent acute neck trauma
• Concomitant severe systemic diseases (e.g., cardiovascular, hepatic, renal, hematological, or psychiatric disorders)
• Pregnancy or breastfeeding
• Known allergy to acupuncture needles or herbal fumigation components
• Receipt of other neck pain-related treatments (e.g., physical therapy, medication, or acupuncture) within the past month
• Presence of open wounds or skin lesions in the treatment area
• Any patient not meeting the inclusion criteria

Individual participant data will not be shared due to confidentiality agreements and the study protocol's data management provisions. Data will be used solely for research purposes by authorized research personnel and will not be publicly available. Reasonable requests for data access may be submitted to the corresponding author after study completion, subject to institutional approval.

Outcome assessors and data analysts are blinded to group allocation. Participants and acupuncturists are not blinded due to the nature of the fumigation intervention.